RESUMEN
The first UK epizootic of highly pathogenic (HP) H5N1 influenza in wild birds occurred in 2008, in a population of mute swans that had been the subject of ornithological study for decades. Here we use an innovative combination of ornithological, phylogenetic and immunological approaches to investigate the ecology and age structure of HP H5N1 in nature. We screened samples from swans and waterbirds using PCR and sequenced HP H5N1-positive samples. The outbreak's origin was investigated by linking bird count data with a molecular clock analysis of sampled virus sequences. We used ringing records to reconstruct the age-structure of outbreak mortality, and we estimated the age distribution of prior exposure to avian influenza. Outbreak mortality was low and all HP H5N1-positive mute swans in the affected population were <3 years old. Only the youngest age classes contained an appreciable number of individuals with no detectable antibody responses to viral nucleoprotein. Phylogenetic analysis indicated that the outbreak strain circulated locally for ~1 month before detection and arrived when the immigration rate of migrant waterbirds was highest. Our data are consistent with the hypothesis that HP H5N1 epizootics in wild swans exhibit limited mortality due to immune protection arising from previous exposure. Our study population may represent a valuable resource for investigating the natural ecology and epidemiology of avian influenza.
Asunto(s)
Animales Salvajes/virología , Brotes de Enfermedades/veterinaria , Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H5N1 del Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Distribución por Edad , Animales , Anseriformes/virología , Anticuerpos Antivirales/sangre , Hemaglutininas Virales/genética , Gripe Aviar/inmunología , Gripe Aviar/mortalidad , Gripe Aviar/virología , Datos de Secuencia Molecular , Filogenia , Factores de Tiempo , Reino Unido/epidemiologíaAsunto(s)
Servicio de Cardiología en Hospital/organización & administración , Grupo de Atención al Paciente/organización & administración , Especialización/tendencias , Enfermedades Vasculares/terapia , Predicción , Alemania , Necesidades y Demandas de Servicios de Salud/tendencias , Humanos , Enfermedades Vasculares/diagnósticoRESUMEN
A solid-phase red cell adherence (SPRCA) assay has been developed to screen blood donors for IgA deficiency, and 6117 donor sera have been screened by this method. Eighteen sera were found to be IgA deficient, which represents a frequency of 1 in 340. Seventeen of these sera were retested by passive hemagglutination inhibition, which has a sensitivity of approximately 0.1 mg per dL. Eight sera were confirmed as IgA deficient, and nine were found to contain low levels of IgA (less than 1 mg/dL). The approximate sensitivity of the SPRCA assay is 1 mg per dL. The speed, simplicity, and sensitivity of this assay make it a good alternative to conventional methods of screening.
